Hi
I am aware that the tittle of this thread does perhaps not reflect the content of this post any longer, but in order to keep all my posts regarding oil changes in one thread, and thereby making them easier for other/new members to read in sequence, I will nevertheless post them here.
Since a few weeks, I have had my BCS 740 for 10 years, and been very pleased with the performance of the tractor and also with the engine. As I also passed 300 hours on the tractor almost on the date, it was time for some serious maintenance. Part of this was the fourth engine oil change, the fourth change of the oil filter and the third change of the transmission oil.
As mentioned in post #10, I again jacked the tractor up and removed the left hand wheels (front PTO-mode) for better access to the oil filter. First though, I connected one of my implements, to prevent the tractor from tipping over. I also removed the engine protection bar for better access to the 2 engine oil drain plugs. As I now had free access to the recoil starter, I removed that and cleaned it and the cooling fan for debris, while the hot engine oil was running out of the engine.
In order to get as much transmission oil out as possible, I have found it useful to tilt the tractor, so that the engine sits on the ground. For that, I put on the wheels again and disconnect the tractor from the implement. Again I do this just after using the tractor, and while the oil is still hot. After removing the oil cap, I leave the tractor with the engine sitting on the flor for the night, allowing all oil to drain.
The above picture shows the magnetic oil cap after 300 hours. To me it looks like the amount of metal particles are almost the same as after 200 hours - perhaps slightly less.
As mentioned before, there are still quite a lot of metal particles on the cap for my liking. Perhaps I worry too much, but the metal particles on the magnetic cap have to come from somewhere, and the metal must be „missing“ there - or not? When comparing to the Honda motorcycle that I had in the 1970s, and where there were hardly any metal parts on the magnetic cap, my guess is that chips perhaps comes from the gear wheels. Compared to a car or motorcycle, our 2-wheel tractors have a very simple sliding-mesh non-synchronized gearbox with straight-cut spur gears. As we have probably all experienced, this means that engaging a gear or the PTO can be tricky, and might be accompanied by a bit of noise when the gear wheels are grinding. I guess this is where the chips comes from, even though I try to do my best to avoid grinding of course.
Another important part of the 300 hour maintenance of the Honda engine, is checking/replacing the spark plug, and checking - and if necessary adjusting - the valve clearance.
My spark plug looked just fine, and the gap was 0.7 mm as required, so I decided not to replace it.
In order to check the valve clearance, I carefully lower a little screwdriver down the spark plug hole until it touches the piston top. By slowly rotating the engine by pulling the starter grip, it is easy to see when the piston is at TDC (top dead center) on the compression stroke. In this position both rocker arms are free to move as both valves are closed. If there are tension on the rocker arms at TDC, the piston is at the end of the exhaust stroke, and the engine most be rotated a complete revolution to bring the piston back to TDC, but now at the end of the compression stroke!
My intake valve clearance was exactly 0.15 mm as it should be, so no adjustment was needed. The exhaust valve on the other hand, had a clearance of 0.35 mm, or almost double the recommended 0.20 mm! This didn’t come as a big surprise to me, as the compression release system hasn’t worked properly for some time. Due to the excessive clearance, the compression release system can’t open the exhaust valve that little bit to allow part of the compression pressure to escape. This means that it is much harder to pull the starter, and that is has a nasty habit of kicking back. To prevent this from happening in the future, I will check the valve clearance every 200 hours instead, and if necessary adjust accordingly.
As a final task I of course cleaned the air filter, and now I look forward to many trouble free hours with my tractor again
Best regards
Jens